<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>Blank</title>
    <style>
        html,body{
            height:100%;
            margin:0;
            display:flex;
            flex-direction: column;
            align-items:center;
            justify-content:center;
            background-color: #eeeeee; /* 浅灰色背景 */
        }
        .info-text {
            font-size:24px;
            margin-bottom:20px;
            color:#333333;
        }
        .back-btn {
            font-size:20px;
            padding:10px 20px;
            background-color:#2196F3;
            color:white;
            border:none;
            border-radius:6px;
            cursor:pointer;
            transition:background-color 0.3s ease;
        }
        .back-btn:hover {
            background-color:#1976D2; /* 按钮 hover 加深蓝色 */
        }
    </style>
</head>
<body>
<div class="info-text">这是一个网页文件</div>
<button class="back-btn" onclick="window.history.back();console.log('尝试回退上一页')">返回上一页</button>

<script>
    // 回退失败时控制台提示
    if (window.history.length <= 1) {
        window.onload = function() {
            console.log('当前已是最前页面，无法回退');
        };
    }
</script>
</body>
</html>